Method for producing half-tone reproductions



March 17, 1942. H. M. CROSBY METHOD FOR PRODUCING HALF- TONEREPRODUCTIONS Filed March 31. 1941 Patented Mar. 17, 1942 METHOD FORPRODUCING HALF-TONE nEPaopUo'rroNs Harold M. Crosby, Flushing,-N. Y.,assignor to News Syndicate Co. Inc., NewYork, N. Y., a corporation ofNew York Application March'31, 1941, Serial No. 386,002

' .4 Claims. (01. 41-41 Myinvention relates to-a new and improved methodfor producing half-tone reproductions.

One of the objects of the invention is to provide improved means forpreparing the copy in chromatic color, so as to make it unnecessary touse dyes or pigments for this purpose.

Another object of my invention is to provide a new'and improved methodfor producing the copy for making a half-tone negative which is known inthe art as a highlight drop-out.

Another object of the invention is to provide an improved method ofpreparing the copy for use in the processes which are set forth in myapplication Serial No. 344,845, filed July 11, 1940, and in myapplication Serial No. 368,186, filed on December2, 1940. a 7

Other objects of the invention are set forth in the annexed descriptionand drawing.

Heretofore, advertising copy of the art work type has been supplied toa: newspaper or other According to the first method, I impregnate thesheetof paper or board on which the copy is prepared with an aqueoussolution of para-nitrophenol. This solution is prepared by dissolving100 grains (avoirdupois weight) of para-nitrophenol in 2 quarts ofwater. I also preferably dissolve grains (avoirdupois weight) of citricacid in the water. Since one pound avoirdupois is equal to 7,000 grains,and since the weight of a gallon of water is 8.3359pounds, said solutioncontains substantially of the para-nitrophenol by weight. The citricacid is used in order to stabilize the solution of thepara-nitropublication, in the form of a drawing in black or gray color,on white copy paper or copy board.

Said drawing almost invariably has areas to i which little or nocoloring matter has been applied. These areas are designated astheextreme highlights."

In the aforesaid applications Serial No., 344,- 845, and Serial No.368,186, I have disclosed the idea of producing the. color tones of thecopy,

save in the very dark tones, in a chromatic color,

such as yellow, yellow-green, etc; I have also disclosed the use ofpigments or the use of watercolors.

The drawing illustrates a subject which has been reproduced by printingwith a half-tone phenol and to maintain the same colorless. Otherwise,the solution assumes a yellow color, upon standing. The citric acid isused in suflicient proportion to maintain the pH of the solutionslightly below '7.

After the copy paper or copy board has been thoroughly saturated withthis solution, the

water is preferably evaporated so that dry copyv paper or copy board issupplied to the artist. It is unnecessary, although it is preferable, toevaporate the water from the copy paper or copy board.

A yellow color can then be developed by reacting the para-nitro-phenolor its aqueous solution, with an aqueous solution of a suitable alkali,

dyes, including such as sodium hydroxide or potassium hydroxide or thelike. This solution can be'made by dissolving 50 grains (avoirdupoisweight) of sodium hydroxide in two parts of water. 2 ounces of sodiumcarbonate can also be dissolved in the water, although the sodiumcarbonate can be omitted. If the entire surface of the copy paper orcopy board is first impregnated with the solution of thepara-nitro-phenol, the paper can be printed subject consist s er areas 4which are' printed in middle or intermediate tone. The printed subjectalso has areas 5, which are printed in'blacktone. Instead of producingthese tones for the original copy or subject in black and white, or ingray and white, said tones are produced in said original copy or subjectin a suitable chromatic color, such as yellow, save for the very darktones, which may be produced in black. The original copy therefore hasno black or grey, save in the very dark lines or areas 5,

' which are drawn in black, and save for the outline of said originalcopy I According to this invention, the copy can be prepared accordingseveral methods.

thoroughly dried, and the artist can make his outline drawing thereon.If desired, the outline drawing can be made before the copy paper orcopy board is treated with the para-nitro-phenol. The aqueous solutionof the alkali can then be applied by means of a brush or in any otherconvenient manner, to all the areas of the copy, except the highlightareas. This produces a uniform yellow color tone in all the areas of thecopy, save for the highlight areas. This color tone is of suitablebrightness and density, due to the proper proportioning of thepara-iiitro-phenol and the sodium hydroxide or the like. After the paperhas been dried, or before it has dried, the darker tones can be producedin the respective areas-of the copy. by using black or dark pigments invarying proportion. I can use lamp black or any suitable grey or blackpigment.-

pension, such as the well-known water' colors. The areas 2 of the copywhich correspond to the light half-tone areas are not treated with thedarkening pigment or pigments. Such darkening pigment or pigments arefapplied in increasing proportion to the areas of the copy whichcorrespond to the middle or intermediate tone, the dark-half-tone, andthe dark tone. The color tones of the respective areas of the copy thuscorrespond to the color tones which are to be produced by half-toneprinting.

If desired, the artist can first prepare a line copy, which willindicate the various areas thereof and the outline of the copy, and thecopy board or copy paper can then be treated so as to develop the yellowcolor, save in the highlight areas of the copy.

The above method may be reversed, by initially treating the copy paperor copy board with the solution of the alkali, and then subsequentlyusing the solution of the para-nitro-phenol. The solution which is firstapplied to the copy paper orcopy board may be designated as the initialsolution, and the second solution may be designated as the developingsolution.

As another alternative, the solution of the alkali may be intermixed invarying proportion with lamp black and other dark pigments, so as toform a number of batches of the alkali solution of varying darkness.These batches can then be 2,276,718 These pigments are preferably inaqueous susmuch more even and fia't in tone, than if a p ment or dye isutilized. Likewise, 'the time and expense of producing the original copyin chro-' matic color is greatly diminished.

For convenience, the areas of the original subject or copy whichcorrespond .to the highlight areas of the printed reproduction may bedesignated as the highlight areas of the original subject, and therespective areas of said original subject or copy may also be designatedas light, intermediate, dark and black.

Whenever -I referto copy paper in a claim or claims, I include anysuitable absorbent material on which the original copy is prepared.

It is well known that numerous color eifects can be secured with the useof various indicators, such as phenol phthalein and the like, but thedevelopment of a bright yellow color by the reaction above described ismuch superior for the specific purpose herein stated.

I can use meta-nitrophenol, as an equivalent for para-nitrophenol.

I have shown preferredembodiments of my, invention, but it is clearthat-numerous changes and omissions can be made without departing fromits spirit.

I claim:

- 1. A method of preparing original copy on paper for use in making ahighlight drop-out, which consists in producing a'yellowchromatic tonein selected areas of said original copy, with the exception of thehighlight areas of said original copy, "by reacting para-nitro-phenoland the solution of an alkali in the selected areas of the The copyPaper or copy board is thus free of the initial solution, save at therespective nonhlight areas thereof. The developing solution, free fromdarkening pigment, can then be sprayed or otherwise applied over theentire surface of the'copy paper or copy board, since the yellow colorwill not be developed save in the predetermined areas of the copy. Thisis preferable, because it eliminate the danger of overrunning of thecolor, and this method is more convenient.

After the original copy has thus been prepared by any of the alternativemethods above mentioned, the subsequent steps of producing the half-tonenegatives are the same as those stated in either of the aforesaidapplications Serial No. 344,845 and Serial No. 368.186.

Whenever I referto the use of darkening pigment, I include the use ofany coloring matter, including a dye or dyes.

Since the areas of th copy which correspond to the printed black areas 5are in deep black tone, it is unnecessary to develop the yellow color insaid respective areas. ofthe original copy or subject.

- The use of a developed yellow color, as, above mentioned, is muchsuperior to the use of a yellow dye or yellow pigment. The developedcolor ispaper.

2. In the art of preparing original copy on paper for use in making ahighlight drop-out, said original copy haying highlight areas and havingother selected areas which are darker than said highlight areas, thatstep which consists in producing a yellow color in said selected areasby first applying an initial solution only to said selected areas of thecopy and then applyin a second solution to all the areas of the copy,said first and second solutions being respectively selected from a classwhich consists of a solution of para-nitro-phenol and a solution of analkali.

3. In the art of preparing original copy for use in making a highlightdrop-out, said original copy having highlight areas and having otherselected areas which are darker than the highlight areas, that stepwhich consists in producing a yellow color tone in said selectedareas byreacting para-nitro-phenol and an alkali in said selected areas.

4. A method of producing original copy on paper for use in making a,highlight negative, said original copy having highlight areas and havinga plurality of series of selected areas of successively darker colortone, which consists in producing a yellow color tone in said selectedareas by reacting para-nitro-phenol and an aldesired color tones thereofby coloring matter' whose tone is darker than said yellow color.

HAROLD M. CROSBY.

